The present invention relates to a spur gear arrangement and to a gearing system having accommodated therein a spur gear arrangement, and to a wind power plant with such a gearing system.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
There is an increasing need for providing bearings for spur gears that have minimal shaft diameter and high mechanical load capacity, while the bearings should still require minimal space. Furthermore, a spur gear arrangement should be easy to assemble and cost-effectively to produce. These demands are increasingly sought in the field of gearing systems, in particular planetary gears for wind power plants.
FIG. 1 shows a longitudinal section of a conventional spur gear arrangement, generally designated by reference numeral 40. The spur gear arrangement 40 has a spur gear 10 with a toothing 11 and is mounted to a shaft 12 for rotation about an axis of rotation 15. The shaft 12 has recesses 20 for supply and discharge of lubricant 25. A central one of the recesses 20 in the shaft 12 has hereby a return port 27. The shaft 12 is fastened between side panels 14, 16 of a planetary carrier (not shown in more detail), which side panels 14, 16 have a supporting wall thickness 17 in the region of the ends of the shaft 12. A lubricant supply 22 in the shaft 12 is supplied with lubricant via the side panel 16, with lubricant 25 being routed via bores 31 to lubrication pockets 28. The lubrication pockets 28 are provided on a surface of the shaft 12 and during operation form a lubricating film 29, on which two plain bearing bushings 18 are rotatably supported. The spur gear 10 is, in turn, received on the plain bearing bushings 18 and rotatable about the axis of rotation 15 by means of the lubricating film 29 between the shaft 12 and the plain bearing bushings 18. The plain bearing bushings 18 are arranged at a distance from one another, with an intermediate space 36 being defined between the plain bearing bushings 18. The intermediate space 36 is delimited in an axially outer direction, indicated by arrows 33, by front faces 45 of the plain bearing bushings 18. Furthermore, the intermediate space 36 is delimited by a circumferential projection 19 of the spur gear 10. The terms “axially outer” and “axially inner” relate hereby to the intermediate space 36. Arrows 33 indicate in FIG. 1 the axially outer direction, and arrows 37 indicate in FIG. 1 an axially inner direction. The terms “radially outer” and “radially inner” relate to the axis of rotation 15. The radially outer direction is indicated in FIG. 1 by arrow 21, and the radially inner direction is indicated by arrow 23. On account of the axial lengths 38 of the plain bearing bushings 18, their axially inner front faces 45 rest on the projection 19 of the spur gear 10. The axially outer ends of the plain bearing bushings 18 extend essentially flush with the spur gear 10. The axial length 38 of the plain bearing bushings 18 corresponds in each case to less than half of the spur gear thickness 13. Thrust washers 30 are arranged in the region of the respective axially outer end of the plain bearing bushings 18 to assist a normal operation of the spur gear 10. A bearing diameter 35, which corresponds essentially to the diameter of the shaft 12, is defined by the lubricating film 29.
It would be desirable and advantageous to provide an improved spur gear arrangement to obviate prior art shortcomings.